In many applications, utilizing point sources of light present challenges for developers and providers of products thereof. Examples of point sources are for instance different type of semiconductor light sources such as LEDs and OLEDs.
Further development of LEDs (Light Emitting Diodes) e.g. higher luminance, have opened new areas for their use. For instance, LEDs may nowadays be utilized in general lighting applications such as luminaires. Thereby the advantages provided by LED technology, such as narrow bandwidth lighting, enhanced control, and low energy consumption, may be utilized in previously unexplored fields of use.
However, the use of LEDs in general lighting has required quite high demands on the optics used because of e.g. the high brightness provided by the LEDs.
TIR (Total Internal Reflection) collimators are widely used to shape LED light into a usable beam. They usually consist of an entrance portion, where the LED light is coupled into the light guiding medium, a tapered light guiding part to collimate the beam, and an exit window where the light beam leaves the light guiding medium. The exit window may be smooth, but it can also contain subtle structures to shape the beam further. For example, the beam width may be broadened by applying a frosted surface or a lens array on the exit window as shown in FIGS. 1a-c. FIG. 1a shows optics 15 having circular lenticulars 16 for shaping the light beam at an exit location of a lighting device (not shown). Similarly, FIGS. 1b-c show optics 15 with straight lenticulars 17 across the exit window, and frosted glass 32 respectively.